The value of endoscopic rectal ultrasound in predicting the lateral clearance and outcome in patients with lower-third rectal adenocarcinoma

Background and study aims: The aim of this study was to assess whether preoperative endorectal ultrasound (ERUS) is able to predict histological infiltration of the external anal sphincter or the levator ani muscle in patients with a lower-third rectal neoplasm and so the possibility of treatment by sphincter-saving surgery.

Patients and methods: Between May 1996 and May 2003, 66 patients with a lower-third rectal neoplasm that was staged as uT2 or greater were entered into a prospective evaluation of ERUS. All patients underwent neoadjuvant treatment before surgery.

Results: The first ERUS (ERUS 1) was performed before neoadjuvant treatment; the second ERUS (ERUS 2) was performed between the end of the radiotherapy and the surgery. An abdominoperineal resection was performed mainly when the lower extent of the tumor was within 3.5 cm from the anal verge (P = 0.011), but no correlation was observed between the lateral clearance determined by ERUS 1 and the histological clearance (P = 0.091). After neoadjuvant treatment, the ERUS 2 lateral clearance was significantly correlated with the type of surgery (P = 0.003) and the histological clearance (P < 0.001). With regard to the performance of ERUS 2 for predicting histological infiltration of the external anal sphincter or the levator ani muscle, the sensitivity was 100 %, the negative predictive value was 100 %, the specificity was 87 %, and the positive predictive value was 53 %. In a multivariate analysis, the histological clearance and tumor T stage were statistically correlated with disease-free survival (P = 0.035 and P = 0.05, respectively).

Conclusions: ERUS could help oncologists and surgeons in the management of patients with lower rectal carcinomas. Moreover, ERUS is able to predict lateral histological clearance after neoadjuvant treatment.

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